Method of recording and reproducing sounds



(No Model.)

T. A. EDISON.

METHOD OF RECORDING AND REPRODUGING SOUNDS. No. 393,967. Patented Dec. 4, 1888.

A TTOHIVEYJ,

N4 Puzas. Pholo-Liihngnphar, Waihinglun. n. c.

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LLEVVELLYN PARK, NESV JERSEY.

METHOD OF RECORDING AND REPRODUCING SOUNDS.

SPECIFICATION forming part of Letters Patent No. 393,967, dated December 4, 1888.

Application filed July 1'7, 1883. Serial No. 280,209. (No model.)

T 0 all whom it may concern.-

Be it known that I, THOMAS A. EDISON, a citizen of the United States, residing at Llewellyn Park, in the county of Essex and State of New Jersey, have invented a certain new and useful Improvement in Phonographs, (Case No. 791,) of which the following is a specification. v

For the recording-surface of my phonograph (i. 6., the phonogram-blank) I employ a solid material, such as a wax composition or a mixture of metallic soaps capable of being indented by the recording-point. In recording sounds a groove is formed in the material by means of an indenting-point connected with the diaphragm of the recorder, and this groove varies in depth accordingly as the indenting-point is advanced or withdrawn by the vibrations of the diaphragm, thus forming the wave-record from which the sounds are reproduced, as is well understood.

Heretofore the recording-point used has been constructed so that in forming the groove it removed the material by a scraping action. This was due to the factthat the advancing edge of the recording-style used was perpendicular to the recordin -surface or receded from the perpendicular, the result being ascraping rather than a true cutting of the material. The scraping action I have found to be, productive of false vibrations, which become a part of the record, and which are audible as scratching and other foreign noises when the sounds are reproduced. I have found that this difficulty is overcome by employing a recording-point made as a true cutting-tool with a cutting-edge in advance of the stock of the tool. It might be supposed that a cutting-tool would be unsuitable for the recording-point, and that the heel of the tool would strike the bottom of the groove and prevent the formation of a perfect record, or obliterate the record as made by smoothing or pressing out the indentations more or less; but I have found that the movement of the recording-surface is sufficient to keep the heel of the tool clear of the indentations. This adaptability of the cutting-tool form for the recording-point I consider is also due in a measure to the fact that the recording-point in my phonograph is arranged to act more or less obliquely to the recordin gsurface, so that the recorded waves will begin gradually and end abruptly. This oblique movement may be accomplished in any of the ways described in my application No. 786, (Serial No. 280,204, filed July 17, 1888,) in which this particular matter is more fully explained. The recording-point in its forward movement advancing against the movement of the recording-surface, the cutting-tool will clear itself just to the extent that its movement advances from the perpendicular, and thus the speed of the recording-surface will be supplemented in the respect of serving to keep the heel of the tool clear by the oblique movementof the cuttingtool. The waves, being abrupt, need not be as deep, and hence there is less (li'fiiculty in clearing th e tool.

In my phonograph the cutting-tool record.- ing-point is carried by a lever which takes the lateral thrust of the tool and relieves the diaphragm of the strain due to that thrust. This carrying-lever is also pivoted so as to produce the oblique movement of the recording-point before referred to. It also is made light, is provided with frictioinbearings to overcome the momentum of the diaphragm and attached parts and to take up lost motion, and it is also positively connected with the diaphragm by a pivoted link or other form of connection which willyield in the direction of the length of the lever, so as to prevent the straining of the diaphragm. \Vhile I prefer to employthese several details, yet it is evident that the cutting-tool can be used with phonograph recorders of various constructions, and hence I do not wish that feature of my invention, except when specially indicated by the claims, to be limited to the details stated. The cutting of the record in the material of the recording-surface, instead of scraping it, makes a clean smooth record, free from imperfections, producing scratching or other foreign noises in the reproducer.

In the accompanying drawings, forming a part hereof, Figure 1 is a view, on an exaggerated scale, illustrating the formation of a record by a scrapingstyle, as heretofore. Fig. 2 is a similar view illustrating the use of this invention. Fig. 3 is a vertical section of my phonograph-recorder complete, and Fig. 4 is a bottom view of the recorder.

A is the recording-surface, which may be 1 given and an inspection of Figs.

considered as a wax composition capable of being indented by the recording point or style. It is given a movement in the direction of the arrows, Figs. 1 and I-Ieretotore the recording-style B hashad its advancing edge perpeiulicular to the recordingsurtace or receding from it, as shown in Fig. 1. This produced the record (I by a scraping action. By my invention the recordingpoint C, Fig. 2, is a cutting-tool having a cutting-edge, I, in advance of the stock ol the tool. This produces the record 1: by a true cutting action. The style 1 is attached di rectly and. only to the diaphragm l3, and hence the wave-record (1 is composed of waves having a synnnetrical rise and fall with the deepest part of each wave at its center. The point C. is mounted on a. pivoted lever, 7, connected with the diaphragm I) by a pivoted link, 1). The direction of movement of the cutting-edge ot the reeording-point is described by the dotted circle (1; hence it will be seen that the recording-point acts obliquely to the recordbig-surface and produces recorded waves, which begin gradually and end abruptly. It will be seen that such is the character of the wave-record (a By the movement of the recording surfacc and the obliqueaetion of the recording-point the heel of the cutting-tool, forming the recordingpoint, is kept clear in operation.

From the description that has already been and 4: it; will be readily understood how my phonograph-recorder is constructed. The lever (1' is carried by a bearing-pin, E, which is pivoted in a yoke, c, secured to the annular frame F of the recorder. A spring, f, bears against the pin E, and is adjusted in its tension by a screw, g. This produces a friction at the bearings of the pin E, which overcomes the momentum. of the diaphragm and attached parts by retarding their movement, and also takes up all lost; motion at the l'icarings. The spring-friction produces a non-resilient and constantly-acting retart'ling device. The pivoted link I) prevents the diaphragm from being strained by the differences in movement of the diaphragm and the recording-point by reason ot the fact that the link, due to its pivots, yields in the direction of the length of the carrier-lever, while it; forms a positive connection between the recording-point and the diaphragm.

I do not claim in this application the machine or apparatus herein described, but only the method of operation, I having been re quired by the (ommissioner ot' ,Iatcnts to embody the a 'lparatus in a separate application for Letters Patent.

\Vhat I claim isl. The method ol' recording sounds for reproduction, consisting in impressing soundvibrations upon a cutting recordingpoint and thereby cutting in the recortling-surface the record correspomling to the souml-waves in contradistinetion to the formation of such souml-records by a scraping action.

The method of recording sounds for reproduction, consisting in impressing soundvilin'ationsupon a cutting recording-point,and directing the vibrations of such recordingpoint obliquely to the rccording-surface and thereby cutting in the recording-surtace a sound-wave record having waves more abrupt at one end than at the other in contradistim-- tion to the formation of such sound-rcmlrds by a scraping action.

This specification signed and witnessed this l-tth day of July, isss.

THUS. A. EDISON.

\Vitnesses:

\VILLLUI lELzEn, A. W. RIDDLE. 

